HMRC boss Dave Harnett failed to win the backing of ministers yesterday, despite apologising over the blunder that left 1.4 million people owing £2billion in tax.

He had made a dramatic U-turn after initially insisting he had nothing to say sorry for to those hit with shock demands.

But Treasury Chief Secretary Danny Alexander avoided publicly backing to the under-fire revenue chief. Asked four times during an interview if he supported him, he replied: "He was right to apologise."

Harnett, who earns £160,000 a year, had said: "I am deeply sorry that people are facing an unexpected tax bill. I apologise if my remarks came across as insensitive."